Think silly to solve this funny math :)

There’s a charming little brain teaser that’s getting shared on everybody's Facebook wall..  It’s got various forms, but they all look something like this:
This problem can be solved by pre-school children in 5-10 minutes, by programer – in 1 hour, by people with higher education … well, check it yourself! 

• 8809=6
• 7111=0
• 2172=0
• 6666=4
• 1111=0
• 3213=0
• 7662=2
• 9313=1
• 0000=4
• 2222=0
• 3333=0
• 5555=0
• 8193=3
• 8096=5
• 7777=0
• 9999=4
• 7756=1
• 6855=3
• 9881=5
• 5531=0
• 2581=?

Here ya go…
The answer has to do with how many circles are in each number. So the number 8 has two circles in its shape(well..should say, count the eggs in each number..lol)  so it counts as two(eggs). And 0 is one big circle, so it counts as 1. So 2581=2. Ok, that’s cute, it’s an alternative mapping of values with implied addition.